I just bought a 2006 BMW 330i with the logic7 system yesterday and love it, but I would like to install and aftermarket sub and amp. Best buy seems afraid to touch it because they said it has fiber optic speaker wire and they can't just wire in a line out converter from the stock HU and run those RCAs to a new amp/sub. Is this true? What would I have to do to add some bass to the sound? Any help is greatly appreciated!